Communication system tonal component maintenance techniques

Abstract

An apparatus and method for suppressing noise is presented. The apparatus may utilize a filter bank of bandpass filters to split the input noisy speech-containing signal into separate frequency bands. To determine whether the input signal contains speech, DTMF tones or silence, a joint voice activity & DTMF activity detector (JVADAD) may be used. The overall average noise-to-signal ratio (NSR) of the input signal is estimated in the overall NSR estimator, which estimates the average noisy signal power in the input signal during speech activity and the average noise power during silence. Two indirect power measures are performed for each band, measuring a short-term power and a long-term power. The power estimation processes are adapted based on the signal activity indicated by the JVADAD. A NSR adapter adapts the NSR for each frequency band based on the long-term and short-term power measures, the overall NSR and the signal activity indicated by the JVADAD. The NSR adaptation may then be performed. The gain computer utilizes these NSR values to determine the gain factors for each frequency band. The gain multiplier may then perform the attenuation of each frequency band. Finally, the processed signals in the separate frequency bands are summed up in the combiner to produce the clean output signal. In another embodiment of the present invention, a method for suppressing noise is presented. An alternative embodiment of the present invention includes a method and apparatus for extending DTMF tones. Yet another embodiment of the present invention includes regenerating DTMF tones.

1. A method for maintaining integrity of an input tonal component of a communication signal comprising:
 detecting a presence of the input tonal component; 
 generating a supplemental tonal component based on the input tonal component; 
 matching frequency and phase of the supplemental tonal component to frequency and phase of the input tonal component; 
 validating at least a partial detection of the input tonal component; 
 generating an output signal to maintain the integrity of the input tonal component based on validation results; and 
 transmitting the output signal. 
 
     
     
       2. The method of  claim 1  wherein the communication signal includes an input speech component and an input tonal component. 
     
     
       3. The method of  claim 1  further including combining at least a part of the input tonal component and a part of the supplemental tonal component to generate the output signal upon obtaining validation, the output signal having a time duration greater than a time duration of the input tonal component. 
     
     
       4. The method of  claim 1  further including generating the output signal upon obtaining non-validation, the output signal including the communication signal in an unsuppressed state. 
     
     
       5. An apparatus for maintaining integrity of an input tonal component of a communication signal comprising:
 a detection module to detect a presence of the input tonal component; 
 a first generation module to generate a supplemental tonal component based on the input tonal component; 
 a frequency matching module to match frequency and phase of the supplemental tonal component to frequency and phase of the input tonal component; 
 a validation module to validate at least a partial detection of the input tonal component; 
 a second generation module to generate an output signal to maintain the integrity of the input tonal component based on validation results from the validation module; and 
 a transmission module to transmit the output signal. 
 
     
     
       6. The apparatus of  claim 5  wherein the communication signal includes an input speech component and an input tonal component. 
     
     
       7. The apparatus of  claim 5  wherein the second generation module is configured to combine at least a part of the input tonal component and a part of the supplemental tonal component to generate the output signal upon obtaining validation from the validation module, the output signal having a time duration greater than a time duration of the input tonal component. 
     
     
       8. The apparatus of  claim 5  wherein the second generation module is configured to generate the output signal upon obtaining non-validation from the validation module, the output signal including the communication signal in an unsuppressed state. 
     
     
       9. The method of  claim 1  further comprising detecting a frequency and phase of the input tonal component, and wherein matching the frequency and phase includes matching the frequency and phase detected. 
     
     
       10. The method of  claim 3  wherein combining at least a part of the input tonal component and a part of the supplemental tonal component to generate the output signal is based on a weighted average combination to maintain the integrity of the input tonal component, the output tonal component having a time duration greater than the input tonal component. 
     
     
       11. The method of  claim 1  wherein input tonal component and supplemental tonal component include a dual-tone multi-frequency (DTMF) signal. 
     
     
       12. The method of  claim 1  further including processing the input tonal component in blocks of samples. 
     
     
       13. The method of  claim 12  further including detecting the presence of the input tonal component after processing a predetermined number of the blocks. 
     
     
       14. The method of  claim 12  further including detecting the input tonal component during a first received block of the input tonal component. 
     
     
       15. The apparatus of  claim 5  further comprising a second detection module to detect a frequency and phase of the input tonal component and the a frequency matching module further configured to match the frequency and phase using the frequency and phase detected. 
     
     
       16. The apparatus of  claim 7  wherein the second generation module is configured to combine at least a part of the input tonal component and a part of the supplemental tonal component to generate the output signal based on a weighted average combination to maintain the integrity of the input tonal component, the output tonal component having a time duration greater than the input tonal component. 
     
     
       17. The apparatus of  claim 5  wherein the input tonal component and supplemental tonal component include a dual-tone multi-frequency (DTMF) signal. 
     
     
       18. The apparatus of  claim 5  further wherein the apparatus is configured to process the input tonal component in blocks of samples. 
     
     
       19. The apparatus of  claim 18  wherein the detection module is configured to detect the presence of the input tonal component after a predetermined number of the blocks have been processed. 
     
     
       20. The apparatus of  claim 18  wherein the detection module is configured to detect the input tonal component during a first received block of the input tonal component. 
     
     
       21. A computer-readable medium having stored thereon sequences of instructions, the sequences of instructions including instructions, when executed by a processor, cause the processor to:
 detect a presence of the input tonal component; 
 generate a supplemental tonal component based on the input tonal component; 
 match frequency and phase of the supplemental tonal component to frequency and phase of the input tonal component; 
 validate at least a partial detection of the input tonal component; 
 generate an output signal to maintain the integrity of the input tonal component based on validation results; and 
 transmit the output signal.